How Does Work Affect the Energy of a Helium Nucleus?

[ohheytai]

A helium nucleus has mass 3.4e-27 kg. If its speed |v| is 0.939c (that is, |v|/c = 0.939), what are the following values?
particle energy = 8.897e-10 J

rest energy = 3.06e-10J

kinetic energy = 5.83e-10J

i found those but now i can't figure this out:

Next an electric force acts on the helium nucleus and does 4.2x10-9 J of work on the particle. Now what are the following values?
particle energy = J

rest energy = J

kinetic energy = J

please help me!

 

[venkatg]

You have to use the relativistic equations

Rest energy = E = M * C * C
Total energy = Rest energy + K.E
(No, K.E is not 0.5 m*v*V!)

As the v/c = 0.939, we can not ignore relativistic effects

relativistic factor g = 1/sqrt((1- (v/c)^2)

So total energy = rest energy * g

K.E = total energy - rest energy

 

[ohheytai]

i know that idk how to do it when there is a force i already solved for that

nvm figured it out thanks